201300041

 

 National Transportation Safety Board

 Washington, DC 20594

Office of the Chairman

March 26, 2013

The Honorable Michael P. Huerta

Administrator

Federal Aviation Administration

Washington, DC 20591

Dear Administrator Huerta:

Thank you for the Federal Aviation Administration’s (FAA) January 15, 2013, letter to 

the National Transportation Safety Board (NTSB) regarding Safety Recommendations A-09-43, -44, 

-46 through -51, and -53, stated below. We issued these recommendations to the FAA on 

July 8, 2009, as a result of our investigation of the June 28, 2008, ground fire before engine startup 

of ABX flight 1611, a Boeing 767-200, at San Francisco International Airport, San Francisco, 

California.

A-09-43

Require operators to replace electrically conductive combustible oxygen hoses with 

electrically nonconductive hoses so that the internal hose spring cannot be energized.

A-09-44

Prohibit the use of electrically conductive combustible oxygen hoses unless the 

conductivity of the hose is an intentional and approved parameter in the design.

We are encouraged that the FAA has issued the airworthiness directives (ADs) and 

completed the evaluations of several other manufacturers’ oxygen system designs, and that your 

agency has concluded that the designs evaluated to date pose no safety concerns. Pending the 

completion of your reviews and the issuance of appropriate ADs, Safety Recommendations 

A-09-43 and -44 remain classified “Open—Acceptable Response.”

A-09-46

Require airplane manufacturers and modifiers to provide positive separation 

between electrical wiring and oxygen system tubing according to, at a minimum, 

the guidance in Advisory Circular (AC) 43.13-1A, “Acceptable Methods, 

Techniques, and Practices–Aircraft Inspection and Repair,” and AC 65-15, 

“Airframe and Powerplant Mechanics Airframe Handbook.”
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A-09-47

Require airplane manufacturers and operators to ensure that oxygen system tubing 

in proximity to electrical wiring is made of, sleeved with, or coated with 

nonconductive material or that the tubing is otherwise physically isolated from 

potential electrical sources.

The FAA’s requirement for electrical wiring interconnection system (EWIS) maintenance 

programs, effective March 10, 2011, completes the FAA’s actions to satisfy these 

recommendations in an alternate manner; consequently, Safety Recommendations A-09-46 and 

-47 are classified “Closed—Acceptable Alternate Action.”

A-09-48

Develop minimum electrical grounding requirements for oxygen system components 

and include these requirements as part of the certification process for new airplanes 

and approved supplemental type certificate [STC] modifications to existing airplanes.

A-09-49

Once electrical grounding requirements for oxygen system components are 

developed, as requested in Safety Recommendation A-09-48, require airplane 

operators and modifiers to inspect their airplanes for compliance with these 

criteria and modify those airplanes not in compliance accordingly.

A-09-50

Develop inspection criteria or service life limits for flexible oxygen hoses to 

ensure that they meet current certification and design standards.

A-09-51

Once inspection criteria or service life limits for flexible oxygen hoses have been 

developed, as requested in Safety Recommendation A-09-50, require airplane 

operators to replace those hoses that do not meet the inspection criteria or that 

exceed the service life limits.

Although the FAA believes that existing airworthiness standards are adequate for

addressing the issues raised in these recommendations, the agency also believes that new policy is 

needed to clarify compliance with these standards. We believe that the revised policy and 

guidance may address the issues for new airplane designs and new STCs, but these revisions will 

not mandate a change for airplanes currently in service with previously approved designs.

Pending the development and issuance of those revisions, Safety Recommendations A-09-48 and 

-50 are classified “Open—Acceptable Response.” 
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Regarding Safety Recommendations A-09-49 and -51, we disagree with the FAA that 

there is not sufficient basis for applying the proposed revisions to airplanes in service. However, 

because the FAA does not plan to take the actions specified in Safety Recommendations A-09-49 

and -51, they are classified “Closed—Unacceptable Action.”

A-09-53

Require operators of transport-category cargo airplanes to install smoke detectors 

in the supernumerary or similar compartment of their airplanes.

We disagree with the FAA that the actions already taken to address the root cause of the 

ABX flight 1611 accident are sufficient to prevent further events, and we continue to believe that 

mandating smoke/fire detection within all existing supernumerary areas and remote crew 

rest areas is warranted. Although the FAA’s policy may constitute an effective response for new 

installations, similar actions are also needed for existing airplanes. Accordingly, pending 

issuance of the policy memorandum, and similar action being taken to address in-service 

airplanes, Safety Recommendation A-09-53 is classified “Open—Unacceptable Response.”

We encourage you to submit updates regarding these safety recommendations

electronically at the following e-mail address: correspondence@ntsb.gov. To avoid confusion, 

please do not submit both an electronic copy and a hard copy of the same response.

Sincerely,

cc: Ms. Camille Mittelholtz, Acting Director

 Office of Safety, Energy, and Environment

 Office of Transportation Policy